i-pad locked

I have a i-pad that talks to me. When . push the lower button on my screen.The screen is lock that I can't slide to sign in.Also at the top right corner (when you touch it. It say's donot disturb). I already tried to push both the(wake up button/sleep button and the bottom button). and try to reboot and that does nothing. How can I fix this. please help I looking for advice. Thank you Jake